As the method for monitoring the growing to a film by applying an MOCVD method during the film growing process, there are the ellipsometry and the laser reflectometry .
In 1980, F . Hotter, J . Hallais and F. Simomdet disclosed a technique in which the thickness of a film can be measured with real time without carrying out simulations, and which is based on a structure and analysis far simpler than the existing complicated ellipsometry. (In-situ monitoring by ellipsometry of metalorganic epitaxy of GaAlAs-GaAs super lattice, 51(3),1599).
Meanwhile, in 1991, N. C. Frateschi, S. G. Hummel and P. D. Dapkus disclosed a film monitoring technique which resorts to a laser reflection method utilizing the variation of the interference pattern period of beams which are reflected after irradiating laser beams to a sample. (In-situ laser reflectometry applied to the growth of Al.sub.x Ga.sub.1-x As Braff reflectors by metalorganic chemical vapor deposition, Electronic Letter, 27, 155).
However, in these techniques, if the film grows in the normal manner, then the thickness of the film can be measured. However, if its composition is varied, the variation of the composition cannot be monitored, and therefore, it cannot be confirmed as to whether the variation of the interference pattern period of the reflected laser beams occurring during the growth of the film is due to the growth rate of the film, or due to the variation of the composition.